Breakdown of alten alte alter
gut
good; fine; well
die Frau
the woman
der Kaffee
the coffee
So you see that our coffee is masculine. There are very few, close to no rules about which is what gender, just try to learn them with memos like German coffee is for tough guys
ist
is
alt
old
der
of the - feminine, plural
Elon.io is an online learning platform
We have an entire course teaching German grammar and vocabulary.