You need to grant a service account full control of the Managed Metadata service on Farm

HOTSPOT
An organization has two SharePoint farms named FarmA and FarmB.
You need to grant a service account full control of the Managed Metadata service on Farm A.
In Central Administration, which command should you select to complete the configuration? (To
answer, select the appropriate command in the answer area.)

Answer:

Explanation:

Note:
Example:
Event ID: 8077
Message “There are no instances of Managed Web Service is started on any server in the farm.
Ensure that at least one instance is started on an application server in the farm using the Services on
Server Page in Central Administration.”
Solution:
Your SharePoint Admin Account or System Account that you are using to browse the Central
Administration does not has access to service Application so
Go to Manage Service Applications Page
Select Managed Metadata Service Application Row

From Ribbon Click Permissions
Now Add your Admin account contoso\SP_Admin in my case. Click Add and give him all 3
permissions and click OK.
Setting Up Managed Metadata Service Application SharePoint 2013