Constitutional liberalism is when a country has a special set of rules that protect the rights of its citizens.
Imagine you and your friends are playing a game. After a while, one of your friends tries to change the rules of the game in their favor. You and your other friends might get upset because you all agreed on the rules together before you started playing, and everyone was supposed to follow these rules.
In the same way, a country with constitutional liberalism agrees on a special set of rules, called a constitution. This constitution says how the government and the people should behave with each other. It outlines the rules of the game for everyone to follow, so the government can't change things in their favor and take away citizens' rights.
These rules usually include things like freedom of speech, freedom of religion, the right to vote in elections, the right to a fair trial, and many other important rights that people have.
Constitutional liberalism means that the government has to follow these rules just like everyone else, and that the rules can't be changed easily. It's like a game where everyone agrees on the rules beforehand and has to play by those rules. This helps make sure that everyone is treated fairly, and people's rights are respected.