We will need to use Avogadro's number (#6.022*10^23#) to solve this problem. In case you don't know, Avogadro's number tells you how many molecules, atoms, or chemicals are in a mole of those molecules, atoms, or chemicals. So there are #6.022*10^23# atoms of He in #1# mole of He atoms.
Now, let's get on with the problem. We will need to use dimensional analysis to convert from atoms of He (which was given) to moles of He (what we are trying to find):
#9.033*10^23" atoms He"rarr"moles?"#
#9.033*10^23" atoms He"((1" mole He")/(6.022*10^23 "atoms He"))=?#
#9.033*10^23color(red)(cancel(" atoms He"))((1" mole He")/(6.022*10^23 color(red)(cancel("atoms He"))))=?#
Plug this into your calculator, and you should get a value of #color(blue)(1.500" moles of He")# with the appropriate number of significant figures (#4#).
I hope that helps!
