Trair means "to betray" or "to cheat". It's a strong and emotionally charged verb that immediately hints at the song's central theme of infidelity and moral conflict.
In the context of the song, the singer is pleading with someone to "stop calling me to betray" (Para de me chamar pra trair). This word is key to understanding the internal struggle and the illicit nature of the relationship being described, making it very enticing for a learner to explore.
"Para De Me Chamar Pra Trair" is about resisting temptation. The singer already has someone at home who waits up for her every night and can't sleep until she's back safe, and she doesn't want to lose that. So she's telling whoever keeps pursuing her to stop calling her to cheat.
She admits it isn't the right moment and that they can't keep making mistakes together. She weighs whether she's fair to either of them, but keeps landing on the same answer: it's better to stop this here, for good.