Fibromas are overgrowths of connective tissue. In the oral cavity they occur as firm, well defined "lumps" of uniformly pink tissue. They are not usually bound down to any underlying tissue, so their movement is limited only by the overlying tissue. They generally grow to a particular size (most commonly a centimeter across or less) and then stop growing. They can remain unchanged for many, many years. They are either ignored or removed by an oral surgeon. They are totally harmless unless they interfere with normal functioning. They are not contagious.
This fibroma is in the attached gingiva just under the lower left canine (the patient's left). While most fibromas are freely movable and are not bound down to underlying tissue, this one is non movable. The reason is because the tissue in which it arose is bound down itself. Note that there is no redness which indicates that there is no inflammation, which is one of the distinguishing characteristics of fibromas. This helps the clinician to distinguish a growth like this from a periodontal abscess.