Suppose you're reading a newspaper article like this one from
Libération.fr:
Tardif mea culpa de l'Eglise polonaise. The text deals with the difficult legacy of Poland's Communist past, particularly allegations that some Catholic priests collaborated with the secret police. You need a certain amount of specialist vocabulary, e.g.
prêtre = priest,
paroissien = parishioner,
archevêque = archbishop,
aumônier = chaplain, but you should be familiar with at least the first one, and all except
aumônier can be guessed from their similarities to their English meanings.
At the end of the third paragraph you come to this sentence:
Ce qui lui avait valu deux passages à tabac. You probably know all of the words (
valu is the past participle of
valoir) but a direct translation would make no sense at all.
Valoir generally means 'to be worth', but
valoir quelque chose à quelqu'un means 'to earn someone something'. So the sentence reads 'This earned him ...', but what did it earn him?
From the context we can guess that it is something unpleasant - we are talking about information about him being passed to the secret police - but what does tobacco / a tobacconist's shop have to do with it? This is where it is important to have a good, large dictionary, which includes idiomatic phrases. The Collins-Robert entry for
tabac tells us that the colloquial expression
passer quelqu'un à tabac means 'to beat someone up'. Thus, the whole sentence could be translated as 'This got him beaten up twice' or 'This was enough to get him beaten up twice'.
So,
passer quelqu'un à tabac = 'to beat someone up' - an example of the problems translating word for word. But even if you were in an exam or didn't have a dictionary, common sense would give you some idea what the expression meant. By reading lots of genuine French material, and paying attention to the turns of phrase, you can take your French to the next level. Try the newspaper websites linked to on the right.