Formal: "J'écoute" (pronounced "z-eh-koot")
Informal: "J'entends" (pronounced "z-ahn-ton")
"J'écoute" is the most common and versatile translation. It is used in most situations, including when you are listening attentively or passively.
"J'entends" is more informal and implies that you are aware of what is being said. It is often used when you are being told something, or when you are noticing a sound.
For example:
* "I listen to music" would be translated as "J'écoute de la musique."
* "I hear a noise" would be translated as "J'entends un bruit."