着実なのが

the steady one

→ 着実だ
phrase Rare #41,999
the steady one 着実な means “steady” or “reliable,” and のが turns the adjective phrase into a noun-like subject: “the steady one” or “being steady.”
JA: ゆっくりでも、着実なのが最後には勝つ。
EN: The slow and steady one ultimately wins.

ゆっくり着実なのが競走に勝つ

Slow and steady wins the race.

ゆっくりと着実なのが結局勝つ

Slow and steady wins in the end.

遅くとも着実なのが競争に勝つ

Slow and steady wins the race.

ゆっくりと着実なのが競争に勝つ

Slow and steady wins the race.