The more familiar you are with the language you want to study abroad, the better and more effective your study abroad will be.
Once you know which course you want to take, for how long and where you want to study abroad - then it's time to start with the language preparation. You don't need any prior knowledge of the chosen language, but it's always good to start practising: listen to Spanish music, download an English language learning app or watch a French series on Netflix. The more familiar you are with the language you want to study abroad, the better and more effective your study abroad will be.