Learn Finnish: Milloin sulla on treffit? - When do you have a date?

The word sulla is the standard spoken language (puhekieli) version of sinulla. In everyday conversation, the personal pronouns usually shrink. For example, 'I have' becomes mulla on and 'you have' becomes sulla on.

Since this lesson is about shortened verbs, does the verb on change in spoken language?

No, on stays exactly the same! While first and second person forms shrink (olen becomes oon, olet becomes oot), the third-person form on doesn't change in puhekieli. It pairs perfectly with the shortened pronoun to make sulla on.

Why does the word treffit end in a plural -t if the English translation says 'a date'?

In Finnish, treffit is always a plural word, even when referring to just one romantic date or casual appointment. It works a bit like the English words 'pants' or 'glasses' where the singular concept is grammatically plural.

I remember that the thing you 'have' often takes the partitive case. Why is treffit not in the partitive here?

You use the partitive in a 'to have' sentence for uncountable mass nouns (like sulla on aikaa, you have time) or undefined plural amounts. However, because treffit is a plural-only word acting as a single, complete event ('a date'), it stays in the basic nominative plural form here.