The most common way to treat a squeaky door is with a lubricating oil. The most well-known brand of spray-on oil is WD-40, but other brands will do the job as well. Simply spray the oil onto the hinge and open and close the door a few times. You should find that there is an instant improvement in how well the door moves.
If aerosol oil doesn’t do the trick, then the hinge could be damaged. If the hinge is one of those ‘pin style’ ones, then remove the round pin that holds the plates together, clean it with some wire wool, and then check to make sure that the pin is straight. If the pin is bent then carefully straighten it out with a hammer. Next, check the hinge itself to make sure that it’s free from dirt (use a long nail to scrape out any paint or dust that has accumulated in the hole). Put the pin back in place, and see how the door feels (and sounds) when you move it.
Remember that your door has more than one hinge, so you may have to repeat this process several times. If the hinges are very tight, and WD-40 or another similar spray-on lubricating oil isn’t doing the job, consider rubbing Vaseline into the hinges. This is a thicker lubricant and as such it is more likely to provide lasting benefit.
If none of these treatments work, then you may need to replace the hinges.