A Life Coach is a professional who helps you "optimize" your life and well being. A coach is one who partners with you to--
clarify your goals
identify your own personal strengths and help you learn to leverage them in pursuit of your "best life"
create a step-by-step plan for success/wellness/etc.
keep the motivation high until you reach that goal
solidify the lessons learned, the nuggets you are taking away
appreciate who you are and who you can be at all times
If you are looking for a Life Coach, make sure you ask about their training and certification. (I'd reccomend that they be certified by the International Coach Federation.)
Note that Life Coaches may specialize in type of client (e.g., expats and independent professionals, as I do, or lawyers, single dads, women-who-do-too-much, etc.). Ask about their theoretical perspective. Argentine coaches are trained in "ontological coaching" (google that one). My own training is positive psychology and appreciative inquiry, by the way. Ask for a free consultation and find one with whom you have rapport.
US-trained coaches usually do coaching by phone, meeting clients for a half-hour to 45 minutes a week. The results show you usually do best with at least a 3-month commitment. Prices are generally similar to therapy, but coaching is NOT therapy nor a substitute for it.