Small bumps/lumps on penis without any other problems are usually harmless. It can be an enlarged sebaceous gland or hair follicle. Bacterial infections can cause blister like swellings on the penis but they will be painful and are usually pus filled. If you are sexually active, unprotected sex can result is sexually transmitted infections (STD) like herpes, molluscum contagiosum etc., which can present as small swellings or blisters on penis and slow growing genital warts caused by HPV (Human papilloma virus). Other reasons for swellings on penis may be due to a lymphocele caused by accumulation of lymph when lymph ducts are blocked soon after sex or masturbation. They usually resolve on their own without any intervention.
In your case it is most likely either an enlarged sebaceous gland or hair follicle which is harmless. Do not worry about it and maintain good hygiene and keep your genital area clean. Wear loose undergarments which will allow good air flow.
Hope this helps. Thank you