expression
this is exactly; this for sure; certainly is
Emphatic expression combining こと (abstract thing/matter) with the particle こそ (emphasis/contrast). Used to stress that a particular thing or situation is precisely the case, often in explanations or assertions.
See also: こそ
本を読むことこそが学びの第一歩です。
Reading books is exactly the first step in learning.
彼の言うことこそ真実だ。
What he says is indeed the truth.