Italian is a great complement to Spanish, French and Latin. If you already speak Spanish or French, picking up Italian is quick and easy — and gives you a valuable skill in the global business arena. Phonologically, Spanish and Italian are very similar, so that a Spanish speaking person could effortlessly pronounce Italian. Often times, even without any previous formal training, Spanish speakers are able to understand a lot of Italian (and Portuguese, for that matter), mostly in their written, but often also in their spoken forms. The significant similarities between Spanish and Italian provide mutual intelligibility between them and, indeed, between these two languages and other Romance languages, including Romanian and Portuguese. Moreover, ease of learning Italian exists also for Francophones, due to the high lexical similarity between Italian and French. In terms of lexical similarity Spanish, Italian, French, Portuguese, Romanian are considered sister languages.
Lexical similarity is a measure of the degree to which the word sets of two given languages are similar. A lexical similarity of 1 (or 100%) would mean a total overlap between vocabularies, whereas 0 means there are no common words. Look at the table below, showing some lexical similarity values for pairs of selected Romance, Germanic, and Slavic languages, as collected and published by Ethnologue.
You want to see how many languages belong to the Italic subgroup of the Indo-European Family? Have a look here. You may be surprised!