You can assign a caption to a specific part of a document by inserting a ‘CAPTION’ keyword immediately before it:
#+CAPTION: This is the caption for the next table (or link) | ... | ... | |-----+-----|
Optionally, the caption can take the form:
#+CAPTION[Short caption]: Longer caption.
Even though images and tables are prominent examples of captioned structures, the same caption mechanism can apply to many others—e.g., LaTeX equations, source code blocks. Depending on the export backend, those may or may not be handled.