Mi amas vin (pronounced ME Amas veen) means "I Love you" in the constructed language Esperanto.
Mi equals I.
Amas is the verb Ami (to love) conjugated in present tense.
Vin is the direct object. It is formed by Vi (You) and the ending letter n, which is appended to the direct object in a sentence, thus one can say Vin mi amas or Amas vin mi and it would mean the same.
Also, we can change the ending letter n from Vin to Mi, as in Vi amas min to express the meaning You love me.
See also