External Appearance, Outward Appearance
noun, の adjective
The outside view of you is your external appearance.
がいかん
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.
このアパートメントの外観が好きです。
I like the outward appearance of this apartment.
かなりレトロな外観のビルですね。
It is quite a retro-looking building, isn’t it?
外観の撮影に許可は要りません。
Permission is not required to photograph the exterior.