Most goblins speak only Goblin. Smarter ones often speak Common as well. Hobgoblins and bugbears speak both Goblin and Common—they have more need to, as they are often in charge of bossing around other creatures and need to be able to speak to the creatures they enslave. Dekanter goblins speak Goblin and Undercommon, since they spend most of their lives in the depths of the Dekanter mines.
Goblinoids of all sorts are illiterate, except for those who have player character classes other than barbarian.
Lizardfolk speak Draconic. The more intelligent ones sometimes pick up Common, the better to frighten potential prey. More rarely, they learn languages like Dwarven, Elven, Goblin, Orc, or the language of neighboring home regions, depending on where they live.
All lizardfolk are illiterate, except for those who have a player character class other than barbarian.