Get Similar rows count in mysql

You can use GROUP_CONCAT function for this. Assuming your ddl is something like that

create table users(id bigint, name varchar(50));
create table time_slot(id bigint, u_id bigint, day datetime, time_from time, time_to time);

the sql would be as follows:

select u.id,u.name, ts.day, 
group_concat(ts.time_from, ' - ', ts.time_to ORDER BY ts.time_from, ts.time_to)
from users u left outer join time_slot ts on u.id = ts.u_id
group by u.id, u.name, ts.day
order by u.name, ts.day

See fiddle.