What is unceded Indian reserve mean?

Answer 1

It means that no north American government lays claim to the land. It belongs to the indigenous peoples that habitate it.

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I wouldn't go so far as to say that no government 'lays claim' to the land. If the First Nation refers to the land as a 'reserve,' that in itself would be a recognition of a claim.

There is a large part of eastern Manitoulin Island, in Lake Huron, that the people of the First Nation claim is 'unceded.' The Government of Ontario, however, provides social services and policing. No barrier prevents the First Nation people from leaving or returning, and people living there have Ontario licence plates and Ontario drivers' licences.

To a considerable extent, therefore, the Ontario government certainly 'lays claim' to that land by providing such services to the First Nation people who live there. Without having such a claim, the Ontario Government would be unable to provide those services.