What does it mean to have circle with a dot on one end and a dash - on the other end with solid line on either side

my MacBook Pro froze so I had to hard restart it ( held on button until computer turned off) turned back on , the Apple logo came on then a oval circle with a dot on one end and a dash- on the other end with solid line on each side inside the oval and also a icon that looks to be an on/off switch with arrow pointing up … I have no idea what this is or how to get this off and get my computer to start. Anyone had this happen?