The Premier League outfit will take on the Moldovan champions on Thursday and can qualify to the next stage of the competition if they win in Transnistria and Anzhi Makhachkala draw with Tromso.
"I had never heard of Sheriff before," the London Evening Standard quotes the Germany international as saying. "I thought they were based in Northern Ireland.
"But coming to places like this is always an experience, especially for young players. You learn a lot coming to these types of countries and playing these types of teams.
"It is important to take these kind of atmospheres into your game. You learn a lot of things. So from that point of view it's nice to have a group like this."
Holtby further explained how he came to realise his mistake.
"I only heard of it 20 minutes before we arrived," he said. "I got told it was a country within Moldova.
"That's a new one on me but a good experience to take with me and it has improved my geography.
"I am very pleased to be here. I can tell my grandchildren that I played in a part of Moldova that isn't Moldova."
Tottenham have won all three of their Group K matches so far.