Accent: The tone and modulation of one's voice in speech
Accentuate: To emphasise, to stress up on
Sample 1: The commentator's accent was perfect and impeccable
Explanation: The "modulation in the commentator's voice" was perfect and flawless.
"Accent" is the way we pronounce and the tone / modulation we use in our speech. We would have come across usage of the word in phrases like "British Accent", "American Accent" etc. Every language has a distinct way of being spoken in, when it comes to modulation of voice.
Sample 2: "She had a thick American Accent that suggested her exposure to the American way of life."
Sample 3: "Do not try to put on a fake accent, just speak normally."
Sample 1: "Chronic power shortages accentuate the need for a fresh look into alterative sources of energy generation."
Explanation: Sharp power shortages "emphasise / underline" the need for alternative sources of energy generation.
When you "accentuate" something, you underline its importance.
Sample 2: "Indian cricket team's defeat in the T20 World Cup accentuates the immediate need for rigorous mental and psycholgical training of the players."