Cosecharás comes from the verb cosechar, meaning "to harvest" or "to reap". It's a word often associated with agriculture, but here it's used metaphorically.
In the song, it appears in the phrase "lo que siembras cosecharás" (what you sow, you will reap). This is a well-known proverb about karma, implying that the consequences you face are a direct result of your past actions. It's a powerful and thought-provoking word that adds depth to the song's message of retribution.
"Mejor Que A Ti Me Va" is Andres Cepeda's answer to an ex who expected him to fall apart.
He admits the breakup was hard and the pain took time to leave behind, but he never wished his ex any harm. Now he watches them face the consequences of how they treated him, and life, as he puts it, is paying them back. The hook says it plainly: he is doing better than they are.