If you know the row and column numbers of the value in question, you could use CSS code in the “Custom CSS” textarea on the “Plugin Options” screen of TablePress like

.tablepress-id-N .row-X .column-Y {
	background-color: #ff0000;
	color: #ff0000;
}Code language: CSS (css)

where N (the table’s ID), X (the number of the row), and Y (the number of the column) need to be adjusted to your table.

If you don’t know the row and column numbers (or they sometimes change, or you have more than on value to highlight), I recommend creating a new CSS class for a HTML <span> element. You would then wrap the value in the span tag, like

<span class="highlight-1">your first important value</span>
<span class="highlight-2">your second important value</span>Code language: HTML, XML (xml)

and could create approriate CSS like

.tablepress .highlight-1 {
	color: #ff0000;
	text-decoration: underline;
}
.tablepress .highlight-2 {
	color: #00ff00;
	font-weight: bold;
}Code language: CSS (css)

Here, highlight-1 and highlight-2 are just examples for possible CSS class names. You can adjust these to give their names a meaning, but have to be consistent in HTML and CSS code.

If you would like to changing the styling of rows or cells automatically, based on their content, check out the Row Highlighting and Column Highlighting features that are part of the TablePress premium license plans.