Market protection is a way to protect traders/investors from adverse price movements in the market. For example, if you place a buy market order when the last traded price (i.e. market price) is ₹100 but sellers are available only at ₹600 (for other reasons i.e. low liquidity, high volatility), your order will get executed at ₹600. This, for you, will cause a loss of ₹500.
To protect you from such losses, market orders in options are placed with protection. For example, if you place a buy market order when the last traded price is ₹100, a 5% protection is applied to your order, and your order is placed as a limit order of ₹105. So, your order won’t get executed above ₹105 in any case. If sellers are available at a price less than ₹105, your order will get executed. If not, it will remain open as a normal limit order (with 1-day validity).