This is a guy apologising the only way he knows how: with a song. He opens by admitting the fight was pointless, "estamos molestos, sufriendo por nada" (we're upset, suffering over nothing), and then sneaks in a compliment mid-apology: "te miras linda enojada" (you look pretty when you're angry). Bold move, but it's sweet.
The whole song is the peace offering. He tells her "te hice un par de versos que me salieron del alma" (I wrote you a couple of verses that came from my soul) and that he mixed them with guitar. She's "dueña de mis sueños" (owner of my dreams) and "mi niña adorada" (my adored girl), a very common loving way to address a partner in Mexican Spanish. Even with the fights, "tú tienes el trono" (you have the throne). His closing plea is simple: if we're arguing, "mejor dame un beso" (better just give me a kiss).
Learner tip: "a lo tonto" in "yo te amo a lo tonto" literally means "in a dumb way", but here it means loving someone foolishly, without holding anything back.