"이렇게 알게 된 것도 인연인데 친구 해요." * 이렇게 알게 된 것 = how we came to know each other like this (subject of the sub-clause). * -도 인연인데 = as it is/might be fate that [we ...] (predicate of the sub-clause). (인연 is the Buddhist idea of preordained connections between people, a bit like fate or providence in English) * 친구 해요 = Lets be/make friends (main clause - 우리, "we" or "us" is the implied subject). So it is saying: it means something (like 인연) that we got to know each other, so let's make a friendship out of it. Or "As our encounter must be fate's doing, why don't we become friends.".

이렇게 알게된것도 인연인데 친구해요 i wanna be friend now that it's coincidence that we've met and been familiar.