Two-year-olds come a long way where speech is concerned. But, with rare exceptions, their pronunciation is not crystal clear. Garbled words and difficulty making certain sounds, such as th, w, and s, are common among toddlers and even many preschoolers. Most of this will disappear on its own without requiring any intervention from you. Avoid correcting your child or having her practice the sound. It's certainly not productive to make her feel self-conscious about the way she speaks.
Many parents also fret over delayed speech. If you suspect your child has a problem, consult your pediatrician. If there's a bona fide lag, it should be addressed right away so that appropriate therapy can be started. The possible causes for delayed speech are many and wide ranging. The most common is temporary hearing loss due to repeated ear infections. Other possible causes include a host of environmental and medical problems, even brain damage in very extreme cases.
Some slow-to-talk kids may progress if parents spend time conversing with them often during the day. Others need medical help. In some cases, the problem can be likened to a "wiring problem" in the brain-there's no damage per se, yet the brain is, in a sense, not hooked up correctly. These children are intelligent but may need intensive language therapy to correct the problem.