Canon EOS Rebel T7 Mode D'emploi page 82

Using AF to Focus (AF Method)
You cannot take a picture during autofocusing. Take the picture while the
Live View image is displayed.
80
Focus on the subject.
3
Aim the AF point over the subject and

press the shutter button halfway.
 The Live View image will turn off, the
reflex mirror will go back down, and
AF will be executed. (No picture is
taken.)
 When focus is achieved, the AF point
that achieved focus will turn green
and the Live View image will
reappear.

If focus is not achieved, the AF point
will turn orange and blink.
Take the picture.
4
Check the focus and exposure, then

press the shutter button completely to
take the picture (p.70).