Pecuniary interests occur when you, your spouse or someone else in your house have a financial or business interest in the subject up for discussion. If this is the case, then you must withdraw from the meeting and not take part in the discussion.
However, you mention that it is parish council owned land and so there is still no pecuniary interest as the council and not councillors own the land
If it is a personal interest, one that you have a connection with because your friend is raising the issue, then it is good practice to announce this connection but there is no requirement for you to withdraw and not take part in the discussion. It would also be good practice not to take part and have this minuted so that the residents can see that the council is acting appropriately but this is not compulsory.