I always tell my student's that for the most part nouns that end in -a are "usually" feminine. Nouns that end in -o are "usually" masculine. I say "usually" because the rule doesn't always apply such as with "las llaves". These are some of the exceptions that we have to memorize. As you continue on your language acquisition you will recognize these special gender nouns with out a problem.
What in the world how is the pally wrong!!i didnt know what the word ment so i tapped and it said keys,pally,buddy-buddy and I choise pally just because and the answer is vaults?!?!someone please explain this I am eleven and I have two years to soak up this stuff ........ In other word ...... HELP.....TIME IS TICKING..... no presure ..start typing as fast as lighting .... To save my spanish wanting brain......NOW!!!!!!!!