This is the 586th most frequent Finnish word.
liittyä
To join, connect, or relate to.
Here 'liittyä' means 'to join' or 'to participate in', expressing the action of becoming a part of a group or an activity.
Haluan liittyä mukaan kurssille.
I want to join the course.
Here 'liittyä' again means 'to join', but it is combined with an expression of interest, showing intention.
Olen kiinnostunut liittymään klubiin.
I am interested in joining the club.
Here, 'liittyä' is used to express joining or becoming a member of a group or organization.