〜は〜くらいです
At most, only about… (nothing more)machine translation
FormationA (usually 〜のは) + noun／(verb dictionary form + こと) + くらいです
The pattern Aは Bくらいです narrows the scope down to a minimum: the only thing worth mentioning is about B and nothing more. 私にできるのは、話を聞くことくらいです (about all I can do is listen). Clause A usually takes the form 〜のは (the thing that…), and B is a noun or a verb + こと.
The pattern's nuance is modesty or a mild complaint: the speaker downplays their own ability, or admits there isn't much to tell — 休みの日にするのは、洗濯くらいです (on my days off, about all I do is the laundry).
This is exactly the "downplaying" sense of くらい framed as a full sentence. It pairs naturally with the adverb せいぜい (at most): せいぜい手伝うことくらいです. It points in the complete opposite direction from ほど — ほど exaggerates upward, while 〜は〜くらいです shrinks everything down to "just that much."
Examples
私にできるのは、話を聞くことくらいです。
About all I can do is listen.
休みの日にするのは、洗濯くらいです。
On my days off, about all I do is the laundry.
この町で有名なものは、古いお城くらいです。
The only famous thing in this town is the old castle.