In linux bash scripting, what does >> do in pushd command?

Question

I'm new to learning bash scripting and I'm confused about the following code:

build_web_apps()
{
    for app in $web_apps
    do
        log "Building $app web app..."
        pushed $GIPHY_HOME/../$app >> /dev/null
        ...
        ... (some code)
        ...
        popd >> /dev/null
    done
}

I know what pushd and popd is, but what is the effect of >> in these lines?