Learn Finnish: Älkää tähdätkö tänne!

In Finnish, spatial adverbs are split into static (at), source (from), and destination (to). The verb tähdätä (to aim) implies directing something towards a target. Because of this built-in direction, Finnish requires the destination form tänne (to here), whereas English just uses the static word "here".

Why does the verb end in -kö in this sentence?

It is part of the plural negative imperative. To tell a group of people not to do something, you start with the plural negative word älkää. The main verb must then take its matching negative command ending, which is always -ko or -kö.

How do you form tähdätkö from the dictionary form tähdätä?

Tähdätä is a Type 4 verb. To find the stem for this plural command form, you simply drop the final -a or -ä from the dictionary form, giving you tähdät-. Then you attach the plural negative ending -kö, resulting in tähdätkö.

Could I say this to just one person?

Yes, but only if you are speaking very formally. Älkää tähdätkö is primarily plural, used for two or more people. To tell a single person informally not to aim here, you would use the singular forms instead: Älä tähtää tänne!