Hello! Just start using Mikrotik router. Worry about naming SSID for wifi, what is the best practice, use the same SSID for 2.4 and 5 Ghz wireless network or different like 'Mikrotik5' for 5ghz and just 'Mikrotik' for 2.4?

Both schemes have their merit. When you run both networks on the same SSID you have no control
over which frequency the client will connect, and you may be surprised what happens.
(many clients use 2.4 even when a strong 5 GHz signal is present, sometimes it is possible to change this priority)

When you use two different names you offer the client the possibility to force 5 GHz.

Another option is to run different virtual APs, with both schemes in parallel.
E.g. on the physical APs you set the same SSID and on the 5 GHz AP you create another virtual AP
with the Mikrotik5 SSID and you put it in the same network (bridge). Then clients who select Mikrotik
will do dynamic selection and those who select Mikrotik5 always get 5 GHz.

Another option is to run different virtual APs, with both schemes in parallel.
E.g. on the physical APs you set the same SSID and on the 5 GHz AP you create another virtual AP
with the Mikrotik5 SSID and you put it in the same network (bridge). Then clients who select Mikrotik
will do dynamic selection and those who select Mikrotik5 always get 5 GHz.

doesn't reallly know about virtual AP, thank You for suggestion, it is seems to me more convenient way to setup the router. I will try it, thank again!