I was reading a code saw the following line of the code and am just wondering to know how does this line of code work:

    const roles = Object.values(foundUser.roles).filter(Boolean);

If this is the User Schema:

const userSchema = new Schema({
    email: {
        type: String,
        required: true,
        unique: true
    },
    username: {
        type: String,
        // required: true,
        unique: true
    },
    password: {
        type: String,
        required: true
    },
    roles: {
        User: {
            type: Number,
            default: 2001
        },
        Editor: Number,
        Admin: Number
    },
    refreshToken: [String]
});

I can't understand what does the filter(Boolean) function do? What does Boolean as input mean? What goes to the filter() and what comes out from it?

EDIT: For example if we have a User object that has the default value of roles: {User: {type: Number, default: 2001} , Editor: undefined , Admin: undefined} what would be the value of const roles? [2001] or [User]?