What is Layout Weight in Android?

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="16dp"
    android:paddingRight="16dp"
    android:orientation="vertical"
    android:background="@color/black">
    <Button
        android:id="@+id/b"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="Button1" />
    <Button
        android:id="@+id/b2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="Button2"
        app:backgroundTint="#4CAF50" />
    <Button
        android:id="@+id/b3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="2"
        android:text="Button3"
        app:backgroundTint="#B51ACF" />
</LinearLayout>