How can I fix "no 'access-control-allow-origin' header is present"?

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Javascript

API

vue.js

I am supposed to fetch some user data from a website. I had no problem retrieving the data from Postman, but when I tried to do this with Vue.JS, here we go.

Here is my Users.vue file.

<template>
    <div id="app">
        <div>
            <img src="../Images/imageedit_1_2384739357.png" height=200 width=200 />
            <p>Created by Master PC.</p>

        </div>
        <hr />
        <!--Get the user input here.-->
        <div>
            <form @submit="postData" method="post">
                Email Address: <input type="text" name="userName" v-model="users.mail" /><br /><br />
                Password: <input type="password" name="password" v-model="users.password" /><br /><br />
                <button type="submit">Post</button>
            </form>
        </div>
        <!-- Final Status-->
        <!-- Credits -->
        <hr />
        <div>
            <p>Copyright (C) 2021-2022 - Master-PC.</p>
            <img src='../Images/vlcsnap-2021-06-29-16h05m13s983.png' width="300" height="200" />
        </div>
        <hr />
    </div>
</template>


<script>
    import axios from 'axios'
    import VueAxios from 'vue-axios'
    import Vue from 'vue'
    Vue.use(VueAxios, axios)
    export default {
        name: "Users",
        data() {
            return {
                users: {
                    mail: null,
                    password: null
                }
            }

        },
        methods: {
            postData(e) {
                this.axios.post("[domain name here].com/mail/login", this.users)
                    .then((result) => {
                        console.warn(result)
                    })

                e.preventDefault();
            }
        }
    }
</script>

I expected the results to come out beautifully, like this:

{
    "sysCode": 1000,
    "sysMsg": "",
    "data": {
        "userToken": ----------------------------,
        "isValidated": true,
        "birthday": ---------,
        "gender": male,
        "lastName": ----,
        "firstName": "------",
        "mail": "----------14@gmail.com"
    }
}

Upon entering the user email and password, which is mine, I get this error:

Access to XMLHttpRequest at '[domain name here].com/mail/login' from origin 'http://localhost:1337' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.

What I have tried:

I do not know how to fix this problem here, as I am new to working with APIs with Vue.JS.

I followed this video here:
Vue js tutorial for beginners #24 Post API with form data - YouTube[^]