Learn Romanian: Bucătarul face supa în timp ce eu fac curățenie.

Literally, it translates to 'in the time that' (în = in, timp = time, ce = that/what). It is a conjunction used to connect two actions happening at the exact same time, just like 'while' in English.

Why does the second part say fac curățenie instead of using a single verb for 'to clean'?

Romanian often uses the verb a face (to do/make) combined with a noun to describe an activity. Curățenie means 'cleanliness' or 'cleaning', so a face curățenie literally means 'to make cleanliness'. Here, conjugated for eu (I), it becomes fac curățenie.

Why does the verb a face look different in the two parts of the sentence (face vs. fac)?

Because the person doing the action changes. In the first part, the cook (he/she) is doing the action, so we use the third-person singular form face (makes). In the second part, eu (I) am doing the action, so we use the first-person singular form fac (do/make).

What is the rule for the endings on bucătarul and supa?

These are definite articles, meaning 'the'. In Romanian, they attach to the end of the noun. Bucătar (cook) is a masculine noun, so it takes the ending -ul. Supă (soup) is a feminine noun ending in -ă, which changes to -a to mean 'the soup'.