The winner of the 2020 presidential election will be the candidate who manages to get at least 270 votes in the electoral college. What is the electoral college? It's the American election system in which each state is given a certain number of delegates based to a certain extent on the population of the state, but with slightly more weight given to states with smaller populations. Those delegates cast an electoral college vote for the president based on the election result in their state.
The winner in each state is decided by a simple majority, so if a particular candidate gets 51% of the votes, he (or she) wins all of the electoral college votes for that state. It's all or nothing. That, in combination with the slight weighting preference for states with small populations, means that a candidate can become the president even if the opposing candidate wins the majority of the popular vote.
How many electoral college votes does each state get? You can see that on the electoral college map below.