I figured it out! Thank you so much!

/**
 * Retrieves words threshold value based on field id.
 *
 * @param int $field_id Field id.
 *
 * @return int|null
 */
function buddydev_get_words_threshold_value( int $field_id ) {

	// Field id with no. of words limit. Replace with yours.
	$field_thresholds = array(
	//	1 => 10,
	//	2 => 20,
		3 => 30,
	);

	return isset( $field_thresholds[ $field_id ] ) ? $field_thresholds[ $field_id ] : null;
}

/**
 * Checks if field's data reached their words limit or not.
 *
 * @param int $field_id      Field id.
 * @param string $field_data Field data.
 *
 * @return bool
 */
function buddydev_has_reached_words_threshold_value( int $field_id, string $field_data, int $field_threshold_value ) {

	if ( strlen( trim( $field_data ) ) > $field_threshold_value ) {
		return true;
	}

	return false;
}

add_action( 'bp_signup_validate', function () {
	if ( ! bp_is_post_request() || ! bp_is_active( 'xprofile' ) || empty( $_POST['signup_profile_field_ids'] ) ) {
		return;
	}

	$profile_field_ids = explode( ',', $_POST['signup_profile_field_ids'] );

	foreach ( (array) $profile_field_ids as $field_id ) {

		if ( empty( $_POST[ 'field_' . $field_id ] ) ) {
			continue;
		}

		$threshold_value = buddydev_get_words_threshold_value( $field_id );
		$field_data      = trim( $_POST[ 'field_' . $field_id ] );

		if ( $threshold_value && buddydev_has_reached_words_threshold_value( $field_id, $field_data, $threshold_value ) ) {
			buddypress()->signup->errors[ 'field_' . $field_id ] = sprintf( 'Number of words limit exceeded then field allowed limit which is %d words.', $threshold_value );
		}
	}
} );

add_action( 'bp_actions', function () {

	if ( ! bp_is_my_profile() || ! bp_is_profile_component() ) {
		return;
	}

	// Make sure a group is set.
	if ( ! bp_action_variable( 1 ) || ! isset( $_POST['field_ids'] ) ) {
		return;
	}

	// Check the field group exists.
	if ( ! bp_is_action_variable( 'group' ) || ! xprofile_get_field_group( bp_action_variable( 1 ) ) ) {
		return;
	}

	check_admin_referer( 'bp_xprofile_edit' );

	// No errors.
	$path_chunks = array( bp_get_profile_slug(), 'edit' );
	$field_ids   = wp_parse_id_list( $_POST['field_ids'] );

	// Check to see if any new information has been submitted.
	$error = false;
	foreach ( $field_ids as $field_id ) {

		if ( empty( $_POST[ 'field_' . $field_id ] ) ) {
			continue;
		}

		$threshold_value = buddydev_get_words_threshold_value( $field_id );
		$field_data      = trim( $_POST[ 'field_' . $field_id ] );

		if ( $threshold_value && buddydev_has_reached_words_threshold_value( $field_id, $field_data, $threshold_value ) ) {
			$error = true;
			break;
		}
	}

	if ( $error ) {
		bp_core_add_message( __( 'Words limit exceeded. Please check!', 'buddypress' ), 'error' );

		$path_chunks[] = array( 'group', bp_action_variable( 1 ) );
		bp_core_redirect( bp_displayed_user_url( bp_members_get_path_chunks( $path_chunks ) ) );
	}
}, 5 );

add_filter( 'bp_get_the_profile_field_description', function ( $description ) {
	$threshold_value = buddydev_get_words_threshold_value( bp_get_the_profile_field_id() );

	if ( $threshold_value ) {
		$description .= ' ' . sprintf( 'This Field words limit is: %s', $threshold_value );
	}

	return $description;
} );

I tested it by just using the field id 3 as in your example. However it doesn’t seem to work. When this snippet is activated, the field won’t even update. It “saves” and refreshes, but the content remains unchanged whether I add or remove the text. Also when I add more than the character limit, I don’t get any notification of a problem either. 🙁

Thank you!

That would be wonderful!!