American odds describe what you risk and what you win at $100 increments. -110 means risk $110 to win $100. +250 means a $100 wager wins $250 in profit. Used in the US.
Decimal odds describe what $1 returns including stake. 1.91 means $1 returns $1.91 ($0.91 profit). Used everywhere outside the US — this is the format your spreadsheet wants.
Fractional odds describe profit-to-stake. 10/11 means risk $11 to win $10. Common in horse racing and UK markets.
Implied probability is the win-rate the price implies. -110 implies 52.38% — meaning if you bet -110 200 times, you need to win 105 to break even. This is the only format that matters for evaluating a bet.