Substitute, Replacement
noun, の adjective
You've seen that 代わる means "to substitute for" or "to replace." This is the noun version of that (no う sound on the end). So, what is the noun version of those verb words? It would be substitute or replacement.
かわり
You should be able to figure out the reading from learning 代わる in the previous level.
田中先生はお休みなので、代わりの先生が来ます。
Mr. Tanaka is off, so a substitute teacher will come.
トマトをあげた代わりに玉ねぎをもらった。
I got onions in return for giving tomatoes.
代わりの人は中々見つからなかった。
I had a hard time finding a substitute person.