at present almost every exchange has its trading app. Binance, bittrex, poloniex, hitbtc, kucoin, okex, etc. all have app trading. I personally use several apps. Well, because I trade on several exchanges. like HitBTC, Bittrex, binance. so a good trading app is the property of the exchange itself.
It has actually been a must in this generation for any exchange to develop it's working applications for mobiles, windows, IOS, etc. This has made trading a lot easier. There are platforms which also offer us some benefits like staking, lending, etc through their mobile applications and this has proven to be most useful to earn some revenue by taking no risk.
There are a lot of downloads onto the play store already for such applications. OP might choose a application which seems easy for him to use by going through reviews posted by various users on the app stores. This would also be useful for OP because there are some applications which are most complex to understand and you actually have to make a deep research about those applications itself in order to gain some benefits by using it.