The Erasmus+ Online Linguistic Support (OLS) supports language learning for Erasmus+ mobility participants. The OLS is available in 24 languages, including NL (Dutch), FR (French) and EN (English). The coordinator internationalisation can give you an account. You can also follow a language course at for example Linguapolis (https://www.uantwerpen.be/en/centres/linguapolis/). An alternative would be to depart earlier and follow a language course abroad. That period will be included in your Erasmus stay.