weird facebook link

So today i was chatting with a friend of mine, i mean.. i don't know her in real life. she's older than me about 5 years.. i thought i could met her.. but then she sent me a link.. i never seen that letter before a facebook link, and we are a part of a small community and there are a bunch of trolls too.. some with some knowledge about this kind of thing.. in the past someone spied through a webcam of an user.. anyway, please after this topic will be solved id like to delete everything. this was the link.. the weird thing is the L before facebook. i never seen in all these years a letter before facebook, and more important.. the link didnt look like this at first sight i had to right click it and then copy link, and so.. it was different https://l.facebook.com/l.php?u=https...78&h=uAQElUiAQ i just changed two numbers but not the structure of the URL, nothing too special, just a blue eyed girl gorgeous.. a friend of her. anyway someone can see anything weird in this link? and can explain the 'l' before facebook that i never seen in my life on the social network? (it's true i never liked to much socials but it still look weird to me) not finished. after i opened because i trust this girl.. then i open an application, and the window where to put the password for root privileges changed. 'KDE' im using gnome.. so guys.. thanks for your time, and sorry for the bad english.