Where does “toista” come from?

toista (Finnish) comes from Finnish toinen, from Proto-Finnic toinen, from Proto-Finnic too, from Proto-Uralic to — that.

toista (Finnish): Partitive singular form of toinen; Indicative...

Definitions

Step	Language	Word	Meaning
1	Finnish	toinen	second; other, another; the others, other ones
2	Proto-Finnic	toinen	second; other
3	Proto-Finnic	too	that over there, yonder distal?
4	Proto-Uralic	to	that