ayo, mari - come, come on, let's go
"let's do something together" "or "invitation to do something together"
Makan! = Eat!
Mari makan - come on, let's eat. ( a nicer softer way to say it)
Mari kita cuba - let us try.
Mari kita lihat - let us see.
Mari tepuk tangan - let us clap.
You might also hear,
Kemari - Come here.
Mari - shorter form of kemari.
So if someone say's Mari, Mari.
They can either mean
Come here, come here
or come, come ( a shorten invitation , come let's eat)