Learn French: Le chef reçoit des certificats. - The boss receives certificates.

The verb is recevoir. In French, the letter 'c' followed by 'o' makes a hard "k" sound. To keep the soft "s" sound from the infinitive (recevoir), we add a cedilla before the 'o'. So, il reçoit is pronounced with an "s" sound, rather than a "k" sound.

Does the cedilla stay there for all the present tense forms of recevoir?

No, only when the 'c' is followed by 'o' or 'u'. For "we" and "you", the verb stem changes slightly and the endings start with 'e'. Since 'c' before 'e' is already soft, we write nous recevons and vous recevez without the cedilla. The other forms are je reçois, tu reçois, and ils/elles reçoivent.

Does chef mean "cook" or "boss" here?

It usually means "boss", "manager", or "chief" in a general work context. English borrowed the word specifically to mean a head cook, but in French, un chef applies to the leader of any group or department.

Why use des instead of les before certificats?

Des is the plural indefinite article (the plural of un or une). It means the boss is receiving an unspecified number of certificates (just "certificates" or "some certificates"). If the sentence used les, it would mean he is receiving specific ones: "the certificates".