This is the 382nd most frequent German word.
zeugen
To testify or to procreate.
In this sentence, 'zeugen' is used in the form 'dafür zeugen' meaning 'to testify or provide evidence' in a figurative sense.
Er konnte dafür zeugen, dass sie unschuldig ist.
He could testify that she is innocent.
Here, 'zeugen' means 'to procreate' or 'to bring into existence another life.'
Sie planten, Leben zu zeugen.
They planned to conceive life.
In this context, 'zeugen von' describes the act of demonstrating or being a testament to something, in this case, talent.