It is simply called pronunciation: how a word is spoken, covering its sounds and which syllable gets stress.
Her pronunciation of colleague is clear. This is the noun; pronounce is the verb for saying it.
Do not confuse it with dialect, a whole region's way of speaking, not one word's sounds.
Two learners say schedule differently: one starts the word with a S sound, SKED-jool, and the other starts it with a SH sound, SHED-yool. Both are standard pronunciations; the difference lies in that opening consonant. In another sentence, a learner stresses the wrong syllable of a word, and listeners briefly mishear it. Stress, rhythm, and the vowel and consonant sounds all count as part of pronunciation, not just the sounds alone.
He reads the sentence with a smooth, even rhythm, so his pronunciation sounds natural even though his accent is noticeable. How the words flow together matters as much as saying each word correctly.
One word can have more than one pronunciation. Schedule has a common American form and a common British form, and both are correct pronunciations of the same word.
A dictionary shows this by listing each form separately, so seeing two entries is normal, not an error. Pick the one that matches the variety of English you are learning and stay consistent.