What does Line Capacity: 12/120 mean for a baitcast reel?

Ardent XS1000 baitcast reel fishing

Anyone ever tried these? (I didn't purchase) : r/Fishing_Gear

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Lew's Speed Spool LFS Series Baitcaster Reels 9BB + 1ZRC CHOOSE YOUR MODEL!

Lew's Speed Spool LFS Baitcast Reel

Lew's Speed Spool LFS Series Baitcaster Reel 9BB + 1ZRC CHOOSE YOUR MODEL!

If I put braided fishing line that has a higher pound test than my reel/rod is rated for, but it is the same size as the mono pound test, what will happen?

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Sougayilang Fishing Reel Metal Spool Anti-corrosion Spinning Reel for Saltwate Carp Fishing Pesca Free Line Fishing Tool

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Lew's Tournament MP Speed Spool LFS Series Baitcaster Reels CHOOSE YOUR MODEL!

Our Bass Pro Shops® Johnny Morris® CarbonLite™ Baitcast Reel is strong, smooth, and every bit as fast as you need it to be—with gear ratios from 6.8:1

Bass Pro Shops Johnny Morris CarbonLite Baitcast Reel