Learn Finnish: Mä oikeastaan tiiän, et ne tulee takas. - I actually know that they are coming back.

This sentence is written in everyday spoken Finnish. In casual speech, common function words and adverbs are heavily reduced to make them faster to say. The conjunction että (that) becomes et, and the adverb takaisin (back) becomes takas.

What is the standard written form of tiiän, and why is it spelled this way?

The standard written form is tiedän (I know), from the verb tietää. In spoken Finnish, the weak consonant d is very commonly dropped from the middle of words, smoothly turning tiedän into tiiän.

Why does the verb tulee look singular when the subject ne means "they"?

In standard written Finnish, you would say he tulevat (for people) or ne tulevat (for things). However, a major rule of spoken Finnish is that ne is used for both people and things, and the verb always drops the plural ending, matching the 3rd-person singular form instead. So, it becomes ne tulee.

How is the word oikeastaan formed?