Since version Minecraft PE 0.16.0 the developers have added support for mods, so-called add-ons extension *.mcworld or *.mcpack which in turn can contain as the texture and modification.

To install Addons now you don't need to use BlockLauncher. Just run the file and it installed automatically. Then go to game settings and activate your addon

If you have downloaded a mod that has the extension *.zip or .*rar you will have to install the addon manually. To begin extract the contents of the files and see which folders are inside. There is directly the folder of the addon you will need to move in /games/com.mojang/behavior_packs but also there may be additionally a folder with the textures that you must move in /games/com.mojang/resource_packs

folder Structure MCPE:

• /games/com.mojang/behavior_packs – used for add-ons
• /games/com.mojang/minecraftpe – don't touch the contents of this folder
• /games/com.mojang/minecraftWorlds – used to install card
• /games/com.mojang/resource_packs – used to set textures (and sometimes for installing Addons)

If you have downloaded a mod that has the extension *.js or *.modpkg read the how to install scripts in Minecraft PE

P. S. If you want to view or change the contents of the file *.mcworld or *.mcpack then change the extension to *.zip and open the file in the usual archiver

For those who do not understand, I advise you to watch a video overview of the installation of the Addons

Currently there is only one common way of installing mods is to install mods using the BlockLauncher. And let's just mention. Mods for BlockLauncher go only with the extension *.js or *.modpkg, so if you have downloaded the archive *.zip or *.rar you must first decompress and see what is inside. If the inside is *.js file will be folders with names like texture or behavior this addon and you need to read installation guide Addons

If your file has the extension *.mcworld or *.mcpack, also read the manual -> How to put Addons in MCPE

How to install mod with the extension *.js or *.modpkg in Minecraft Pocket Edition?

1. Install Block Launcher
   
2. Launch the game using Block Launcher
   
3. Click on the icon of a key appears next to MINECRAFT
   
4. In the popup menu, select ModPE Script or Import script
   
5. Press + and specify the path to our script. You can select a file from your device's memory, or to copy the URL of the js file from the download page fashion