Any language is valid. The will must contain the signature of the testator to be valid. It does not matter if the signature is not legible, or even spelled correctly. So, an X or a dot or even a line would be valid as long as the testator meant it as their signature. Normally the signature should be at the end of the will, but some states will allow it to be anywhere in the will.
Most states require that the signature of the testator be witnessed by at least two witnesses.
There is no need for the witnesses to know what is inside the will, only that they know it is being signed by the testator. Some states require that the witnesses be adults, others do not. But all states require that the witnesses be competent enough to understand that they may need to testify or verify they saw or know of the will being signed by the testator. The witnesses should not be in the will as beneficiaries. Nor, should the witnesses be spouses of any of the beneficiaries.