受累 (shòu lèi) is a separable verb (离合词) meaning 'to be put to trouble' or 'to be inconvenienced'. It's a polite expression often used to thank someone for their effort or to apologize for causing them extra work. You can separate 受 and 累 by inserting a measure word like 些 or a result complement, e.g. 受了累 ('have been troubled') or 受了不少累 ('have been put to a lot of trouble'). The most common form is 受累了 (shòu lèi le), used as a standalone polite phrase like 'thank you for your trouble'.