This is the 16379th most frequent Russian word.
речки
"Речки" means "little rivers" or "streams" in English.
Here, 'речки' is in the genitive case referring to the possession or location related to 'речка' (small river).
Дети играли у маленькой речки.
The children were playing by the little river.
In this case, 'речки' is in the genitive case, indicating the subject of concern, the river 'речка'.
Жители города заботятся о чистоте речки.
The residents of the city take care of the cleanliness of the river.
Here, 'речки' is in the plural nominative case, referring to multiple rivers.