To fully (...) something (until it runs out). this Auxiliary verb works with many (but certainly not all) verbs. The nuance is "with much effort", "exhaustively", "every last one", "finally".
5日かけて夏休みの宿題をやり切った。 彼はフルマラソンを走りきった。
今日はライトノベルを2冊も読み切った。 I finished reading (a surprising amount of) 2 light novels today.
An often-used expression is in the potential negative, 切れない. It describes that you cant finish doing or it is incompletable. This can be because it is too much, or because of inability.
感謝しきれない I can't possibly thank you enough.
lit. "I'm unable to fully express my gratitude you."
あなたの帰りを待ちきれなかった I could not wait for you to (fully) come back.
Youtube: Game gengo N3 #11 - 切れない https://bunpro.jp/grammar_points/切る