A tag is a key-value pair provided by Tencent Cloud. It is used to identify resources on the cloud. You can use tags to classify CVM resources based on various factors such as service, usage, and person in charge. With tags, you can quickly find the corresponding resources you need.
Refer to Authorization by Tag.
Refer to Editing Tags of Specific Resources, and just add multiple tag keys/values in step 4.
One resource can have multiple tags but can only belong to one project.