Inside
noun, の adjective
The inside side is the inside. A little redundant but makes a lot of sense.
The readings are the kun'yomi readings. With 側 you've already learned it. With 内 you've also already learned the reading. Combine them together and you have うちがわ. In case you've forgotten, here's a mnemonic to help you remember that pesky うち portion. What is it that's drawn you inside? "Oo, cheese!" (うち) Cheese has drawn you inside. You're so excited that you exclaim, "Oo, cheese!"
ゾンビを中に入れないために、シャッターを下ろして、内側からカギをかけました。
To keep the zombies out, we lowered the shutters and locked them out from the inside.
右の太ももの内側にトゲがささったみたいです。
I think I got a splinter in the inside of my right thigh.
彼女は、美しさが内側からにじみ出ている。
She oozes beauty from within.