This is the 667th most frequent Japanese word.
たま
"たま" (tama) means "ball," "sphere," or "gem."
The word 'たま' is used to mean 'ball' or 'sphere'.
彼はたくさんのたまを持っている。
He has many balls.
The phrase 'たまに' incorporates 'たま' to mean 'occasionally' or 'once in a while'.
彼女の声はたまにかすれる。
Her voice becomes hoarse occasionally.
The structure 'たまには' is used here to imply 'every now and then' or 'once in a while'.