Perigee raising is complete and the satellite is almost in geostationary orbit. This means if engines are not fired the satellite will remain in the same position. Its orbital period is the same as earth's rotation which is 24 hours.
But the satellite is now almost fixed over 113 East longitude. It has to be moved to 108 E. Which is 1840 kms westward. This is done by raising orbit a little above geo stationary levels which makes it slower (more than 24 hrs). Satellites orbits faster when closer to earth and slower at higher orbit. So by making it temporarily higher it will take longer to complete one orbit. Which means earth's rotation will be faster than sat's orbit making it lag and move westward (reverse will happen if orbit is below geostatioary height). Lowering orbit again when 108 E is achieved to geostationary height will make it stationary again. Engines need to be fired twice at opposite points in orbit to prevent elliptical orbits.