I guess that since you are interested in freediving then you must have swam somewhere outside your bathtub at least once in your life. If so then you also must have tried to go deeper than 1 meter, and if you tried that without equalizing you must have had pain in your ears. Someone may have told you the secret of equalization, and you may have already tried it and practiced.
If not, not to worry, the procedure is quite simple, close your nostrils with one hand and blow out gently against your closed nostrils. You should feel something happen in your ears, unless your tubes are blocked they should pop!
Pressure increases as we dive deeper and the pressure forces your eardrum inwards, hence the pain. When we equalize we are redirecting air outwards to push our eardrums back in a normal position, against the inward pressure from the sea. During the dive air from our lungs passes our mouth into the eustachian tubes, these tubes lead to the eardrum and gently force it back into place.
I have found that the most important rule of equalization is to keep a constant pressure against the eardrum throughout the entire descent, in other words do not equalize in stages, rather keep a comfortable relaxed pressure. Even before the descent I like to equalize before my last inhale and start equalizing during the duck dive until I reach the desired depth. Practice equalizing with least possible effort and never go deeper if you feel any pain in the ears or sinus tubes.
Warning! If you force equalization you risk rupturing the lining between the middle ear and inner ear. It happened to me, the result was vertigo during my dive, luckily I had enough experience to go back safely. Moral of the story: do not over force equalization, if you cannot equalize properly do not dive, take a rest and try again another day.
When I find myself blocked, probably due to mucus, I remove my mask and hold on to the bouy, dip my face in the sea and inhale seawater through my nostrils. It is not pleasant at all, but it does unblock the eustachian (sinus)tubes. If you are familiar with the neti pot, it works using the same principle.
Another good one is the neti pot, it is a good practice to do it regularly, in some places in India they do it as regularly as brushing teeth.
There are also some some jaw exercises which one can do to loosen the sinus and eardrums. By opening your mouth and moving your jaw from side to side. Some freedivers practice this regularly and making equalization easier.