Means cute, I'll miss you, I'll see you soon or anything you think is amazing, hot, etc.
It can mean many different things in different contexts.
A couple walk by. "Llagerr" (aww.. that's cute)
A rollercoaster you think would be great to ride. "Llagerr!"
A really hot guy with a six pack comes up. "Llagerr...<3"
If you are talking about something delicious, you can say "llagger" as in, this tastes really good!
Also said differently in many different contexts such as rolling the r's or the l's or just have ongoing rolled r's.