What does it mean when someone says, "Hi"?

in dutch or in general?

Meaningless when used alone on a private.message to me from a person who has never interacted with me before.

In r/l could be a friendly greeting from someone I know or an annoying interruption from a random person on the street trying to get me to sign up for a monthly drain on my finances.

It doesn't really mean anything, especially if used on its own.

At least it is friendlier than that ghastly "Hey!".

"Hey!" is peremptory shout of warning or admonition, not a friendly greeting.

However the group title is "Dutch Language" so perhaps it means something else in Holland.

"Hi" is an informal greeting used to say hello or to get someone's attention