An entrepreneur asking for £100,000 for 20% of a company is offering a 20% equity stake.
Equity means ownership. In a Dragon's Den pitch, the entrepreneur states how much investment is wanted and what percentage of the business will be exchanged for that money. The percentage is not a fee or an interest rate: it represents a share of the company and potentially a share of its future value.
For example, £100,000 for 20% implies a post-money valuation of £500,000, assuming the proposed deal is accepted on those terms. That calculation is why Dragons often challenge founders about sales, profits and valuation.
The on-screen negotiation may change the requested percentage, and a verbal agreement is not necessarily a completed investment. Due diligence and legal documentation follow the televised pitch. The question asks only for the offered ownership percentage, which is stated directly in the proposal.