If Omni-Channel is not used, user-specific skills can be used in the Live Agent Status Dashboard. The skills can be added with an additional field in the user page layout.
Setup / Object Manager / User / User Page Layouts
Add the field: Skills
Setup / Object Manager / User / Fields & Relationships
Field: Skills
Define Skill values like language skills, product skills, etc.
Setup / users / user
Multiple skills can be assigned to a user.
In the call center setup, Presence State, you need to define that skills from users are displayed.
Select Columns: Add Skills
Skills: Use skills from User
Skills are shown in the Live Agent Dashboard.