This is the 4253rd most frequent Russian word.
яндекса
"Яндекса" is the genitive case of "Яндекс," meaning "of Yandex," referring to the Russian tech company Yandex.
Here, "Яндекса" is the possessive form of "Yandex," indicating ownership, i.e., the features of Yandex.
У сервиса Яндекса много полезных функций.
The Yandex service has many useful features.
In this instance, "Яндекса" illustrates the association of the applications with Yandex.