I have good news: there’s much in common between Portuguese and English when it comes to mass and count nouns. For instance many names such as
farinha, vinho, marmelada, sopa, carne, couro, tecido,
are count nouns if you mean varieties, but are mass nouns if you mean quantity of one variety. So you can say:
Countable: temos aqui muitas farinhas: farinha de trigo tipo 65, farinha de trigo integral, farinha de centeio, etc.
Mass: temos aqui muita farinha.
Countable: temos duas marmeladas: esta é mais doce do que aquela.
Mass: há aqui imensa marmelada: eu não conseguiria comê-la toda nem em três anos
As you can see in the examples above, you can tell a count noun by the use of a number (duas marmeladas) or muitas/muitos (many); and a mass noun by the use of muito/muita/imenso + noun (a lot of + noun).
Now there is a lot in common between Portuguese and English when it comes to count and mass nouns, but there are lots of differences too. And if you want to master them, I have only um conselho: practice makes perfect. No set of rules will do. Keep reading and chatting in Portuguese, and you’ll get a better and better feel of how things work. For instance, vinho works just as wine:
Temos aqui cinco vinhos diferentes [varieties, countable]; temos muito vinho [mass], suficiente para embebedar um regimento.
But cerveja is more complicated. It can be used as vinho in the example above, but uma cerveja can also mean one unit of beer (a glass, a bottle, whatever). So três cevejas diferentes will mean three types of beer, but you can go to a bar and ask for três cervejas, meaning three units. Of course, if they have several brands or units of different sizes, that request will lead to a long conversation if the barman is not too busy. It’s the exact same thing with sumo (Portugal) or suco (Brazil).
Then, as in Enlgish, you have names, such as coelho, pato, sardinha, carapau, which are mass nouns if you mean their meat as food, and are count nouns if you mean individual animals. It works in the same way for trees and their wood:
Em Setúbal podes comer a sardinha e o carapau que quiseres [mass, as much sardine and horse mackerel as you like; it could also be interpreted as count nouns, the one sardine you choose, but that’s not what it’s meant]. Estou cheio: comi seis sardinhas e três carapaus.
A mobília deste hotel é toda de nogueira (walnut wood): foram precisas 350 nogueiras (walnut trees) para a fazer.
Many abstract nouns are typically used as mass nouns only: paciência, caridade, compaixão, pobreza. There are also many, such as alegria, tristeza, ódio, amor, esperança, progresso, that can be mass nouns as in English; but can also be count nouns generally meaning an instance of what the mass noun means:
Havia muita alegria naquela casa. Este filho deu-me muitas alegrias.
Há muito ódio no mundo. O João foi consumido pelos seus ódios.
Este filho deu-me muita alegria is not that different from este filho deu-me muitas alegrias; muitas alegrias implies more explicitly that you were made happy on various occasions. Each of the seus ódios would be the hate he felt for a particular person or thing. But generally you don’t say três ódios, cinco tristezas, etc. They’re only loosely countable.
Coming at last to your examples, you got conselho exactly right: it translates best as piece of advice:
Tenho um conselho para te dar; tenho dois conselhos para te dar.
Informação is more complicated. It can definitely be used as mass noun. The plural informações is very common, but often it could be replaced by the singular without change of meaning. And phrases such as duas informações, três informações, in Portugal at least, are rare. If you are doing detective work asking around for information about someone or something, the plural is the more natural option:
Andou aqui um fulano a pedir informações a teu respeito.
But one you’ve collected all that information, singular and plural can both be used:
Aqui está a informação que consegui recolher sobre o Sr. X.
Aqui estão as informações que consegui recolher sobre o Sr. X
You wouldn’t use the plural option if you had put the information together into a single structured report. But the singular could be used whether you had a structured report or just a collection of loose pieces of information. If you’re talking about a structured body of information, say as that released by an official statistics office, you’ll use the singular.