Gram positive cocci (GPC) are spherical shaped bacteria that retain the purple colour during gram staining. Gram negative bacilli (GNB) are rod shaped bacteria that stain pink on gram staining. Pus cells indicate an inflammatory exudate, and signify an inflammatory pathology.
Urethral swab is usually taken from the urethra for diagnosing urethritis. Urethritis refers to irritation or inflammation of the urethra (the tube that carries urine from the bladder to the outside through the penis). The usual symptoms in men are painful urination or discharge from the urethra, and the opening of the urethra may be irritated. The doctor may also ask about your recent sexual history, since most often urethritis results from a sexually transmitted disease (STD) - such as chlamydia or gonorrhoea. Gonorrhoea could be diagnosed by a urethral swab for staining (Gram negative diplococci - cocci in pairs are seen) and culture. Chlamydia can be diagnosed by an antigen test from the urethral swab.
If tests for STDs are negative, the doctor may conclude that you have nonspecific urethritis (NSU). In your case, a mixture of GPC and GNB on the smear from a urethral swab may indicate normal bacterial flora of the lower urethra.