Collocation is an integral part of natural-sounding language. The way some words typically combine with others to form phrases is called "collocation". You can put any words you like together but if they don't "collocate", they won't sound natural.
For example, in Spanish we say "fuertes lluvias", which is translated into English as "heavy rain". Now, if you translate the Spanish phrase literally, you'd say "strong rains", which would sound odd (or funny) to a native speaker's ears!
To help with this important aspect of language, Oxford University Press published an excellent collocations dictionary which is currently in its second edition. It goes without saying that I am one of the proud owners of such dictionary.
If you want to learn more about the Oxford Collocations Dictionary, click on the picture below.