This means that they are trained differently than the average troop and used in situations or operations which are not standard. Their fighting skills and tactics are slightly different than the skills and tactics taught to other combat troops.
They perform a variety of tasks and operations which will include things like snatches, eliminating special targets such as high value buildings, communications facilities, people, and terrorists. These include just a few of the possible missions which they have been used for in the past. Their range is only limited by the imagination of their commanding officers in the field.
They have been used for unconventional warfare, direct action, combating terrorism, special reconnaissance, foreign internal defense, information warfare, security assistance, counter-drug operations, personnel recovery and hydro graphic reconnaissance as needs surfaced.
They are extremely versatile and very highly trained as you can discern by the number and variety of operations in which they have been used. Each person is an investment and requires years of time and millions of dollars to train.
SEALs are maritime special forces, but they can strike from the land and the air as well as the sea. SEALs (Sea, Air, Land) take their name from the elements in and from which they operate. Their stealth and clandestine methods of operation allow them to conduct multiple missions against targets that larger forces cannot approach undetected.