本人下个月将去NUS工作，现在我的IPA信上有一部分内容，没有看明白它是什么意思，希望各位好朋友帮忙给指点一下，不胜感激！

Temporary Employment Pass

This In-Principle Approval allows the Employment Pass applicant to commence employment for a period of 1 month from the date of this letter provided he has a valid Short Term Visit Pass endorsed in his travel document. However, if the Employment Pass is approved for a duration of 3 months or less, he must collect it before he can commence employment。