How can style text like this in wordpress

Add span tag to text you want background for and apply css- background-color and font-style: italic on span

    <p><span class="red">VDD</span> GND is used for driving the internal logic circuitry</p>

Then add the following into your WordPress CSS (your theme will have a css file, but may have a place to add custom styles in the Dashboard).

.red {
    background-color: red;
    padding: 0px 5px;
    color: #fff;
    border-radius: 3px;
    display: inline-block;
    -webkit-transform: skew(-10deg);
    -ms-transform: skew(-10deg);
    transform: skew(-10deg);
    -moz-transform: skew(-10deg);
    -o-transform: skew(-10deg);
}