A career counselor can help you to identify jobs in which you could be successful, inform you about what jobs require in skills and education, and help you map out a plan to transition into a new field. It can be very difficult to take a lifetime of experience in one field and write an effective marketing document that is aimed in a totally different direction. When people think of having skills, they think of things for which they went to school, had training, or which they learned along the way. The ability to program a computer is a learned skill that is most often thought of as tangible. It can be formally taught, requires some form of formal education, can be measured and demonstrated easily.
Transferable skills are more ephemeral.
For example, the ability to negotiate successfully is a transferable skill for which I often look. It isn't something that is normally learned in school or in a class. It is a skill that is beneficial to have in various fields and industries. A teacher often has excellent negotiation skills. If that teacher wants to make a career change into sales, negotiation is going to be a benefit in the new field.