Intro

If you are new in mobile app development and want to make carrier in this field then react native is the best for you

Lets take a new path

For learning something new starts with zero. First you have to learn Javascript from basic to intermediate level.Here is the best resource you should follow from scratch.

W3schools

w3school is the king maker in web development field. You should go through each and every section of javascript at least twice.

freecodecamp

in this you should go through javascript section and solve maximum problem as you can

React

Learn react from react official documentation page and also w3schools react section you have to grasp deeper knowledge about props, state and lifecycle method

Udemy

If you want learn through an instructor then i suggest udemy is the best platform for this section.
i learned react with stephen grider he is the best teacher in my point of view for react and javascript.

Start Journey

If you want to learn new technology the best method is to create projects as you can. This is the part where you have to stay motivated and also keep away from negative thoughts of your mind
Sometimes you feel you can't but trust me you can !
You probably heard sometimes practice makes perfect.