make build will use docker to:

• create db container and app database in it
• install vendor dependencies using composer
• create and configure app container, apply yii2 migrations and launch yii2 server at the port :80 of docker host

you could also:

• make term to get bash prompt at app container
• make mysql to get mysql prompt at db container
• make chown to change ./app folders owner uid and gid to the ones of user executing command (because docker run under root file created by it belongs to root uid and gid)
• make stop to stop db and app containers (also trigges make chown)
• make or make run to start db and app containers
• make clean to remove db and app containers