How does react transfer variables from the parent component state to the child component? (using the antd design framework)

for example: parent component A contains a checkbox,. Now you need to click checkbox to save the selected state (true/false) to the variable checkFlg and pass it to child component B.
Code is as follows:
parent component A

checkInfo = (e)=>{ //checkbox
        this.setState({
            checkFlg:e.target.checked
        });
        // this.state.checkFlg = e.target.checked;
        console.log("1:" + this.state.checkFlg);
    }
// B
<ActiveForm name1={this.state.checkFlg}/>

Sub-component B

:{this.props.name1}

the current effect is as follows (you only need to pay attention to the red box)

Jan.26,2022
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