What's the difference between using the/a/(nothing) in this sentence? What's the difference between definite and indefinite article? What about not using them at all - would it be still correct? "Breaking the/a/(no article) boundaries of fear."
Breaking a boundaries doesn't work because a/an can only be used with singular nouns. Boundaries is plural.
Both breaking the boundaries and breaking boundaries are fine, the former implying all the boundaries, and the latter implying some of the boundaries.