The general applications of computers include data collection, organization and management, communication and image processing. Specific computer applications vary from discipline to discipline and generally include use of subject-specific software.
Computers allow us to capture large datasets (say from imaging), organize them in particular patterns or formats, manage them efficiently and analyze them. The Internet has revolutionized communication and businesses depend on emails and Skype (or other chatting or conference apps) for communication, recruitment, project management, etc. Specific software, say that for banks or oil companies, enables faster jobs in these areas. People cannot only work within the confines of their company, they can also use computer for freelance business. One can write or read books, manage photos and music, carry out cash transactions, shop and even earn money by using computers. E-commerce has enabled buying and selling of products on computers. Similarly, they can be used for educational purposes, i.e. to enhance an employee's knowledge set.
In essence, computers make life a lot easier.