This is the 927th most frequent Russian word.
онлайн
Online.
The word 'онлайн' is used as an adverb modifying the verb 'учу', describing the mode of learning.
Я учу русский язык онлайн.
I am learning Russian online.
'Онлайн' functions as an adverb here, indicating that the store also serves customers via the internet.
Этот магазин работает и онлайн.
This store operates online as well.
Here, 'онлайн' is part of a compound noun 'онлайн-игре', describing the nature of the game as being internet-based.