What do these symbols mean?

HEIF is the file format used. High Efficiency Image File. You can change that in Settings->Camera->Formats.

The Lightning bolt means you used the flash on that picture.

The person icon means there's an identified person or people in the Photo.

HEIF = High Efficiency Format.

Front camera with flash.

If it does not change the EXIF Meta Data, no.

Nope.