This is the 1723rd most frequent Japanese word.
イケ
"イケ" means "pond" in English.
In this sentence, "池" (ike) means "pond" and is used as a noun to describe the place where the koi are swimming.
その池には美しい鯉が泳いでいます。
In that pond, beautiful koi are swimming.
Here, "池" again refers to "pond" but is part of a phrase suggesting going to a specific location.
今週末、山へ池に行きますか？
Are you going to the pond near the mountain this weekend?
In this context, "イケな" is used as a casual adjective meaning "attractive" or "stylish," modifying "池" to describe a favorable impression of the pond being built.