Rocket.Chat/app/ui-message/client/messageBox/userActionIndicator.html

<template name="userActionIndicator" args="rid, tmid">
	{{#if data}}
		<div class="rc-message-box__activity">
			{{#each data}}
				<span class="rc-message-box__activity-user">{{ users }}</span>
				{{#if multi}}
					{{_ "are" }}&nbsp;{{_ action}}{{#unless end}},{{/unless}}
				{{else}}
					{{_ "is" }}&nbsp;{{_ action}}{{#unless end}},{{/unless}}
				{{/if}}
			{{/each}}
		</div>
	{{/if}}
</template>