Specialty, Speciality, Area Of Study, Major
noun, の adjective
Your specialty gate is the thing you open to let out your specialty. Imagine the thing you're best at (your specialty). Now imagine opening a gate in your chest that lets it out, allowing you to be good at it.
せんもん
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
それは私の専門外です。
That's out of my area of study.
私の姉は、ペット専門の目医者です。
My older sister is a specialty pet eye doctor.
私の専門は天文学です。新しい星を発見したいです。
My specialty is astronomy. I want to discover new stars.