When tables are encountered, the screen reader linearizes the table. This means that it first reads the text in the first column of row one, then the second column, then the third and so on until all columns in that row have been read. It then reads all columns in the second row then the third and so on. This is because designers rarely organize their content in logical rows and columns. Although sighted users can understand the content, it can be very confusing to users with visual impairments.
Some simple practices can make tables much more accessible.
Take a look at our accessible tables tutorial for more information. Simple things such as adding a summary to the table or using table headings properly will go a long way to making the table more accessible.