Biopsy report of buccal mucosa: infiltrating moderately differentiated keratinizing squamous cell carcinoma. What does this means.?

Needs treatment. Means you have cancer of oral cavity ( buccal mucosa ) from your description appear to be localised you will have good prognosis needs further work up for staging &care , by surgical excision for localized small area, or chemo radiation , discuss with your physicians and please do not delay . Good luck.
You have cancer. Untreated, it will kill you. These oral cancers can more often than not be successfully managed by a multidisciplinary team. Wishing you the best.