Tereza is from the Czech Tereza — Czech rendition of Theresa — from the Greek Therasia (possibly to harvest). Tereza is one of the Czech feminine names.
Tereza does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Tereza reduce to 3, The Communicator. This is a traditional interpretive system, not a factual claim about the name.