Question Anyone knows what this is? and what might be the cause??

[shubhamcr7]

Hey, i opened my laptop first time for cleaning it and saw oil/greese type of leak on it not able to wipe it off what may be the cause of this and what is this is it harmful for my laptop in long run?

 

[shubhamcr7]

https://postimg.cc/hh7j1KYv