From this statement, we can deduce that a radioisotope that forms a stable isotope after it undergoes radioactive decay suggests that it does not participate in a decay series.
It could have emitted any form of radioactive particles which can be alpha or beta.
We do not know if it has a long or short half life because the value is not given.
But since the radioactive decay in one step produces a stable isotope, we can conclude that it did not participate in a decay series.
A decay series involves a radioactive decay in multiple steps.
