Learn Finnish: Talvella minä en ole täällä yksin. - In the winter I am not here alone.

The base word for winter is talvi. To say in a season, Finnish usually adds the ending -lla or -llä (the adessive case). When a Finnish word ends in -i, that letter often changes to an e before adding the ending, which is why talvi becomes talvella.

Why do we use en ole for "I am not"?

In Finnish, "not" is actually a verb that changes depending on who is doing the action. For minä (I), the negative verb is en. The main verb olla (to be) loses its normal personal ending, becoming just ole. Together, en ole means "I am not".

Could I drop the word minä (I) in this sentence?

Yes, absolutely! Because the negative verb en already tells us that "I" am the one doing the action, the pronoun minä is optional. Saying Talvella en ole täällä yksin is completely natural. Including minä just adds a little bit of emphasis to the "I".

What exactly does täällä mean compared to other words for "here"?

Täällä means "here" in a broad, general sense, like "in this area" or "around here". You might notice it also has that -llä ending, just like talvella! This ending often points to being at or on a location or time.