If you're celebrating St. Valentine's Day today, you might assume that people in Spanish-speaking countries are celebrating el Día de San Valentín. Indeed that's the case — although it is also known in some areas as el Día de los Enamorados (Day of Those in Love), el Día del Amor y la Amistad (Day of Love and Friendship) and/or el Día del Cariño (Sweetheart's Day or Affection Day).
If you're looking for something appropriate with regard to learning Spanish today, I'd suggest a look at a 5-year-old blog post that has become one of the most popular on this site, and it still gets occasional comments: "Te Quiero or Te Amo?" (I'll warn you, though, that you can't believe all the comments you read.) For a more formal explanation of the difference been two verbs for love, querer and amar, see the lesson on saying "I love you" in Spanish.