This is the 14102nd most frequent Spanish word.
tercert
It seems "tercert" is a typo or doesn't exist as a valid Spanish word. Did you mean "tercer"? If so, it means "third" in English.
Ordinal number indicating position in a sequence.
Hoy es mi tercer intento para aprender francés.
Today is my third attempt to learn French.
Ordinal number representing an additional instance in a context.
Puedo ofrecerte un tercer consejo si lo necesitas.
I can offer you a third piece of advice if you need it.
Ordinal number marking a point in a temporal sequence.