This much; this amount/extent. Used as a noun or adverb to mean 'to this degree'.
これくらいの値段なら買えると思う。
I think I can buy it at about this price.
練習はこれくらいで十分だ。
This amount of practice is enough.
英語で言うと、これくらいの長さです。
In English, it would be about this length.