Potato
White Potato
noun
A じゃが potato is a potato. More specifically, a white potato.
じゃがいも
The reading is the same as what you learned with the kanji.
「じゃが芋の皮、剥ける?」「心配しないで。朝飯前だよ。」
"Can you peel the potatoes?" "Don’t worry. It’s a piece of cake."