How to select correctly?

Question

SQL

There was a question at the interview that I'm trying to clarify. I do not understand what kind of comments in the request. More details https://sql-language.ru/query-select.html
Example No. 5.
Calculate the number of students enrolled in each faculty. Display the name of the faculty in the query, the comment - "training", the number of students, the comment "person".
sql server management studio 17 swears when I try to do this with my table. I can not understand why why and how to write a request so that it works correctly.

Answer 1

select fac, concat('learning ', quo, 'person') as info
from(
select fac, count(*) as quo
from student
group by fac
)q

Answer 2

||' learns '||
This part is not clear to me how it works