Involved in pre-rRNA and tRNA processing. Utilizes the methyl donor S-adenosyl-L-methionine to catalyze the site-specific 2'-hydroxyl methylation of ribose moieties in rRNA and tRNA. Site specificity is provided by a guide RNA that base pairs with the substrate. Methylation occurs at a characteristic distance from the sequence involved in base pairing with the guide RNA. Interacts with nop5. Component of box C/D small ribonucleoprotein (sRNP) particles that contain rpl7ae, FlpA and nop5, plus a guide RNA. Belongs to the methyltransferase superfamily. Fibrillarin family.