Who can be (one of the two) the witness to my will?
Your witness must be above age 21 at the point of signing of the will.
Your witness can be anyone including your guardian/executor/trustee. The only restriction here is that witnesses MUST NOT be beneficiaries nor the spouses of beneficiaries. The term "beneficiaries" includes all beneficiaries, trust beneficiaries, remainder beneficiaries, and any substitutes for these beneficiaries in the Will.
Additionally, the witnesses do not need to read the Will in order to sign off as a witness. The primary function of the witness is to witness the testator signing the Will. Other than the testator, the witnesses nor anyone else needs to know of the content inside for the Will to be valid.