Nodejs `${}’ Value Usage

  node.js, question

Just contacted nodejs and read a piece of code today.${}This value-taking operation is not very clear, so find the solution.
A.js is as follows

module.exports = {
 publicPath:'abc'
 bracket

B.js is as follows:

var a = require('./a');
 
 function buildConfig() {
 var b = {
 publicPath: `${a.publicPath}`
 bracket
 
 console.log(b);
 
 bracket
 
 
 module.exports = buildConfig();

When I executed node b.js, I found that I could print out the value of publicPath defined in a.js