Turkish is a crazy language with crazy grammar logic. In Turkish, it is possible to command/order a person that is not even next to you.
In English, the best translation of this rule would be "Tell him/her to do that" meanwhile in Turkish, you could basically say that with the suffix "sIn".
(Sen) Buraya gel!
(O) Buraya gelsin!
This grammar is actually everywhere in our daily life as common phrases such as "Kolay gelsin, afiyet olsun, Geçmiş olsun, Doğum günün kutlu olsun and Bayramın mübarek olsun" has exactly the same grammar.
Lots of Turkish learners have this question in their mind: "What does "olsun" mean?". As this grammar is not used in English or the other languages (at least the ones that I know), it is impossible to answer this question. But my answer would be "Let it be ...sth..."
"Afiyet olsun" would literally be translated as "Let the food be healthy for you" so that you order/command the food to be healthy.
"Kolay gelsin" would literally be translated as "Let the work come/be easy for you" so that you order/command the work to be easy for the worker.
Meanwhile, in "Allah rahatlık versin" the literal translation would be "May Allah/God give you rest, so that in this case you are ordering/commanding, or let's say "asking" Allah to give the person what they need.
These phrases are usually asked by my students, so I decided to make a list of 3rd person imperative phrases that we have in Turkish. If you know one that I don't include in the list, you can comment below! :) Must know A1 level phrases/prayers
Kolay gelsin - Let the work come easy for you. (Can be told to anyone that's working on something.
Afiyet olsun - Let the food be healthy for you. (Can be told to anyone that's about to eat, currently eating or already done eating.
Geçmiş olsun - Let the illness be gone off your body. (Can be told to anyone who is and has been sick or someone who had a bad experience)
Doğum günün kutlu olsun - Let your birth day be blessed. (Can be told to a birthday person)
Hayırlı olsun - Let it be blessed for you. (Can be told to anyone who bought something new such as car, house, glasses, phone, dress etc.)
Bayramın(ız) mübarek/kutlu olsun - (Can be told to celebrate "Eid" or a national day)
Sıhhatler olsun - Let there be health on you. (Can be told to someone who got a haircut, shave or shower to protect them from any cold wind that could easily make them sick.
Allah rahatlık versin. - May Allah/God give you rest. (Can be told to someone who is about to sleep.)
Allah razı olsun. - May Allah/God be pleased. (Can be used in the meaning of "Thank you" in a conservative way.)
Must know A2 level phrases/prayers
A blog is coming soon.
Must know B1 level phrases/prayers
A blog is coming soon.
Must know B2 level phrases/prayers
A blog is coming soon. Must know C1 level phrases/prayers
A blog is coming soon.