I have an lg lcd 22lk230 tv .. I found two options named hdmi and service only. cannit understand what are they for

Although it appears to be a VGA port, the fact that it says "Service Only" leads me to believe it has a proprietary pinout and cannot be used for any purpose by the consumer (you). If I were to guess I'd think it is set up to allow screen calibration (but I'm not sure).

Edit, the HDMI port is for any HDMI devices (computer or tablet or other that have HDMI out)