This is the 6746th most frequent Japanese word.
ヒポ
"ヒポ" (Hipo) is not a standard Japanese word, but may refer to "hypo" (short for hypochondria or hypodermic) or be a transliteration of "hippo" (hippopotamus). Context is needed for accurate meaning.
Here, 'ヒポ' is used as the Japanese phonetic transcription of 'hippo', commonly referring to the animal hippopotamus.
ヒポは大きなイノシシの種類です。
The hippo is a type of large boar.
In this context, 'ヒポ' is again used to refer to a hippopotamus, emphasizing its typical environment, water.
ヒポが川で泳いでいるのが見える。
You can see the hippo swimming in the river.
'ヒポ' here specifies a particular animal observed by the speaker in a zoo, highlighting learning or recreational contexts.