You speak common.

When you take a long rest, you must spend at least six hours of it in an inactive, motionless state, rather than sleeping. In this state, you appear inert, but it doesn’t render you unconscious, and you can see and hear as normal.

Menhir do not have hands, or even limbs, but you are able to manipulate your surroundings using a limited form of telekinesis.

You may manipulate objects within 2.5ft of your body telekinetically. You may manipulate up to two small objects (weapons, tools) as if using human hands, or up to one larger object (two-handed weapons, furniture, crates) as if using human hands, up to your carrying capacity as determined by your Strength score. Objects worn or strapped to your body impact your carrying capacity as normal. Exceeding your carrying capacity impacts your movement speed as normal.

Without legs, the Menhir hover from place to place. Your movement speed is 0. Your fly speed is 30ft, but cannot take you more than one foot from the ground.

You are a construct for the purposes of spells and abilities which affect constructs.

You have advantage on saving throws against being poisoned, and you have resistance to poison damage.
You are immune to disease.
You don’t need to eat, drink, or breathe.
You don’t need to sleep and don’t suffer the effects of exhaustion due to lack of rest, and magic can’t put you to sleep.

The library's Menhir are very big and made entirely of stone, which makes them very hard to damage. On the other hand, they're very big and made entirely of stone, so they're not particularly nimble. Your Constitution score increases by +3 and your Dexterity score decreases by -2.

The Menhir are very new, and it's not entirely clear how long one might live for. There is every indication that they might go on living indefinitely, unless they are disenchanted or fractured in some way, as many have been.

Menhir usually stand between five feet and seven feet tall. They are usually no more than four feet in diameter. Your size is Medium.

Your body is a natural weapon, which you can use to make unarmed strikes. If you hit, you deal bludgeoning damage equal to 1d4 + your strength modifier, instead of the usual bludgeoning damage for an unarmed strike.

Due to your stony composition and the shape of your body, you are ill-suited to wearing armour. Your body is fairly difficult to damage, however; it gives you a base AC of 17 (your Dexterity modifier doesn't affect this number). You gain no benefit from wearing armour, but if you are using a shield, you can apply the shield's bonus as normal.