Learn Swedish: Hon skapar sin egen framgång. - She creates her own success.

Usually, adjectives after a possessive word (like min, din, or sin) must take their definite form, which ends in -a. But egen (own) is a special exception! It always matches the gender and number of the noun in the indefinite form. Since framgång is a singular en-word, we use egen instead of egna.

Why does the sentence use sin instead of hennes for 'her'?

In Swedish, when a possessive word refers back to the subject of the same clause (She creates her own success), you must use the reflexive possessive sin. If you used hennes here, it would mean she is creating some other woman's success!

How can we tell if framgång is an en-word or an ett-word from this sentence?

We know it is an en-word (en framgång) because the words describing it are in their en-word forms: sin and egen. If it were an ett-word, the sentence would use sitt eget instead.

Does the word framgång mean something else literally?

Yes, it is a compound of fram (forward) and gång (walk or going). In Swedish, 'walking forward' is how you express the concept of 'success'.