"Wir haben gerade Gehalt bekommen" basically means "We just (a short while ago) received (our) salary".
(das) Gehalt can mean:
1) the salary that a worker gets paid by their employer, often on a monthly basis
2) (rare) any form of payment someone gets for doing something for someone
(der) Gehalt means something different, which doesn't fit into the context of your sentence, but be aware that this word also exists.