You have not provided enough information to get an answer to your question. What are you using to record the video? Are you using a phone, camera or camcorder? Who is the manufacturer (Sony, Canon, Samsung, Fuji or someone else) and what is the model number of the device you are using? Some devices have a pause button usually symbolized by "||" (without the quotation marks) while others do not have a pause button and you have to stop recording and then resume recording.
Depends on what manufacturing and model of recorder you are using.
Some models of recorders you cant pause like on dslr cams. Only a small few manufactures has this feature on dslr.
My note 8 all i have to do is press the red record button and once presses the record button turns into II a pause button. Simple as that.
If you dont see a pause feature after you pressed record then you might cant pause.