Mais (more) finds it's way many expressions, always assuming the role of saying most or, more. Let's look at one of the most useful ways mais in Portuguese can say things like: prettier, heavier, saying, younger, newer and etc. (ie, as an adjective).
Look at these really useful examples where mais can help you easily form new sentences and words. You don't need to hung up looking for words like heavier, older and colder. Mais in Portuguese lets you say all of these very easily.
mais in Portuguese
Don't forget that the endings have to match the gender.
O carro é mais novo.
A mesa é mais longa.
A empresa é mais antiga.
O metro é mais caro.
A internet é mais rápida.