Hueva is a very common slang term in Mexico, literally meaning 'egg' (specifically, a male animal's testicle), but colloquially it refers to extreme laziness, boredom, or a general lack of desire to do something. It's similar to saying 'what a drag' or 'I can't be bothered'.
In the song, the artist uses it to express his profound disinterest in seeing his ex-partner again: "Qué hueva volverte a topar en la fiesta" (What a drag to run into you again at the party). It perfectly captures his dismissive and fed-up attitude.
In "BRILLO," Tito Double P sings about the messy end of a relationship. The song's title, which means "shine" or "sparkle," is questioned right from the start: "Di dónde ha quedado el brillo" (Tell me where the shine has gone). The singer feels he gave his all but was treated badly in return, leading him to curse Cupid and try to forget his ex. He claims he's moved on, even joking that "Ya no te extraña ni el perro ni yo" (Neither the dog nor I miss you anymore).
Despite his tough talk and claims of having a better time with friends, there's a clear internal conflict. He admits to having "Sentimientos extraños" (Strange feelings), confessing that while he wants to hate her, he still misses her. Seeing her at a party, dancing flirtatiously, is something he dreads because it's still painful. The song captures that complicated feeling of trying to move on from someone who was all talk and broken promises, while still dealing with the lingering heartache.