The country which has an exclave that shares a border with both Russia and Canada is the United States. The United States exclave which shares a border with both is the state of Alaska.
The United States
The only Latin American country that shares a border with the United States is Mexico.
The United States of America.
Yukon Territory in Canada shares a border with Alaska in the United States.
The United States and Guatemala.
Two countries share a border with the United States. To the north, the US shares a border with Canada. To the south, the US shares a border with Mexico.
Too many to name them all, twelve in the US north and four in the south.
Canada shares a border with six states in the United States: Alaska, Washington, Idaho, Montana, North Dakota, and Minnesota.
The United States shares borders with Canada to the north and Mexico to the south.
Texas is a state of the United States of America. It is not itself a country, and there is no country within the state. There is a country that shares a border with Texas, and that related question is linked below.
New Mexico is a US State and Mexico is a soverign country that shares a border with the United States of America.