There is a pronunciation guide for basic Spanish at the Omniglot website. This includes a pronunciation guide to the Spanish alphabet (or "alfabeto"), enabling users to gain a better understanding of how to sound a variety of basic Spanish words.
Many letters in Spanish vary depending upon their placement within words. The letter B, for instance, is sounded softly, almost as a V sound, when between vowels, and as a hard, labial B sound elsewhere. The same is true of the letter V.
In addition to its Spanish pronunciation guide, the Omniglot website also outlines the differences between pronunciations in European (or Castillian) and Latin American Spanish. The website also features MP3 recordings of native speakers, either reading the alphabet or passages of text.
To further assist in its users learning of Spanish pronunciation, Omniglot provides a list of relevant links to other language websites.
The StudySpanish website is another useful resource for Spanish learners, particularly with its list of tips and tricks for learning Spanish pronunciation. These include speaking aloud at a conversational volume and remembering that the vowel sounds in Spanish are uniform. This guide also encourages learners to allow the trilled "rr" sound to develop with practice and not to get hung up on getting it right early on.