PHP is one of the famous programming language, specially used for website development. Like other programming languages it also has all oops features and properties. Multiple inheritance is not possible in this language but there is alternative way introduced to achieve the same that is traits. Trait is a mechanism to get reusability of codes in php web application. Interfaces are traits which can be implemented in any class and you can define functions in implementing class as per the requirement. A class can implement multiple interfaces and define all methods according to ones need/requirement and this way multiple inheritance is achieved in php using traits/interfaces.
Php is an open source programming language and can be easily learned by surfing internet and watching videos. There are many frameworks and cms have been available in php which are used in website development.
Php version 5.6 is one of the very stable version of php since a long time but php 7.0 is becomming very famous these days because it is very fast and have come with many new and unique features.
You can have a website in php on very low cost to run your business online. It needs mysql database which is available free of cost and there are many hosting companies proving hosting of php websites on very low of cost.