What does Vos mos usquequaque exsisto meus numerus unus mean?

Answer 1

This is an ungrammatical string of Latin words produced by an online translation site in response to the English sentence "You will always be my number one". In fact it means nothing of the sort; translated back into English, it's actually something like "You [plural] custom all the way I emerge my number one".

In any event, numerus unus is not idiomatic in Latin to express "of first importance". For an idiomatic equivalent, we can take a page from the Roman orator Cicero and say "Semper Eris apud me primus, "You will always be first with me". (If this is said to a woman, the feminine form prima must be used instead of primus.)