Perhaps, this pair of words is the most confusing for English language learners. We pronounce 'affect' and 'effect' almost the same way, so the meaning depends on the context.
So, you have to be a very attentive listener. Indeed, there is the only one letter that makes the whole difference! But it is not difficult to understand the difference between 'affect' and 'effect' as it may seem.
So, the first and the main: affect is a verb while effect is a noun. There is a good way to remember the rule. Do you know the bird raven? Of course, you do. Take a look at it from this side:
Remember Affect Verb Effect Noun
Then. Affect means to influence, to impact. For example:
We see five key ways urban planning will be affected in the years to come.
You may have questions about how those loans could affect your financial plans.
How the coronavirus crisis will affect London’s migration dynamics.
Effect is a result or a consequence. For example:
There is a tornado watch in effect for much of eastern North Carolina until noon.
The Tesla effect has changed perceptions of electric transport.
Investors warn of coronavirus crash effect on CEO bonuses.