What's the meaning of If $ ϕ1,ϕ2 ∈ Hom(K^n, K^m) then Mϕ1+ϕ2 = Mϕ1 +Mϕ2 $

Question

I've been asked the following questions:

1. $ϕ_1,ϕ_2 ∈ Hom(K^n, K^m)$ then $ Mϕ_1+ϕ_2 = Mϕ_1 +Mϕ_2 $
2. If $M_1,M_2 ∈ M_(n*m)(K) $ then $ ϕ_(M_1+M_2) = ϕ_(M_1)+ ϕ_(M_2) $

But I don't know what is this meaning. Does Hom means homomorphism? Which subject is this?

Can anyone explain it for me?

Thank you very much!