Hi everyone.
Let me ask a bit about mikrotik.
On their FTTH line, the provider gives 6 static IP addresses on that FTTH line. Now, how do I want to assign one of those static IP addresses to another device via a mikrotik Ether port? Hope you can support or show me the keyword for me to search. Thank you.

it depends on how the provider provides the addresses. You can bridge the uplink port with the one to which the other device will be connected (so Mikrotik firewall won't be able to control the communication of this device), or you can use dst-nat and place the other device into a private lan subnet, or you can use a point-to-point ethernet link where the IP at Mikrotik side and the one at device side are /32 not related to each other (i.e. a private one at Mikrotik)...

6 addresses sound strange to me, is it 5+gateway?